Symptom
After adding DatePicker, set properties and compile, and then the following error message was reported.
/Users/*****/Main.storyboard:1:1: Internal error. Please file a bug at feedbackassistant.apple.com and attach “/var/folders/gm/t2l4p33d1r9gpqzscb8kdggw0000gn/T/IB-agent-diagnostics_2020-12-13_14-22-11_398000”.
Cause
Unknown.
In my case, I added DatePicker with count down timer for macCatalyst. And added a few lines of code to change properties. Then, suddenly the error came up. After removing the DatePicker control and then it was solved. I guess it would be a Xcode bug.
Solution
Clean build and rebuild did not work.
Close and reopen the project did not work.
Restart Xcode did not work.
Removed the DatePicker control and rebuild, then it worked.
